As our lifestyles become more and more complex, we desire devices that enable organization. This helps to bring our lives some sort of normality. Shelving products have evolved since the days of the uncovered “cup boards” in the late 18th century to the modern cabinets with decorator doors and movable shelving as seen today. Though the shelving is typically “movable” it is not easy to move. The shelves must be unloaded, some sort of stop or mounting on two or more corners must be removed, and repositioned, the shelf reinstalled and then the shelf can again be loaded. This is a time consuming and labor-intensive project. As such, it is usually only done when the shelving is installed and never moved again. Many people are unaware that their shelving is movable.
As far a width adjustment, there are very few choices. For the most part this is restricted to buying or building the shelf or bookcase at the desired width. That will never be changed.
There are some “cup rack” type supports that offer a width adjustment. These usually include a base with an extension on one side. One of the problems is since there is an extension on a side the upper surface now has two levels, one for the base and one for the extension. This uneven surface is not only unattractive, but does not lend itself well to stacking items. Also, these devices do not provide for vertical or height adjustment.